The present invention relates to the drainage of soils by means of a porous mass which can also be used for irrigation purposes.
In fact, due to its construction, the mass of the invention allows maintaining the soil in which it is buried in a state of great permeability and, since this mass may be placed according to any disposition, the drainage or irrigation and lightening functions may be carried out without difficulty. The mass of the invention exhibits the feature of being very difficult to clog up and therefore it can keep its properties for a very long time when dispersed in the soil.
A further advantage of the mass of the invention resides in the fact that its constituent elements allow making connections and deviations in all directions and eventually with other drainage devices when they are placed in a trench.
The draining mass of the invention remedies also the problem well known of the specialists who use perforated drainage tubes in the holes of which the roots make their way and tend to proliferate by forming what they call "foxtails".
Where, on the contrary, the mass of the invention is used for irrigation purposes, notably for cultivations on slabs, it forms a kind of soft underground litter which can be fed with water through ducts emerging from the slab. The compressibility of the mass is such that the water has a tendency to be distributed and to re-ascend by capillarity under the effect of the earth pressure. The mass causes also an air circulation, notably if ventilation holes are provided in the support slab, which is very favorable for the life of the crops.
On the other hand, when the constituent elements of the mass are dispersed within the earth on the occasion of a deep ploughing, they contribute to a lightening of the density of the ground by forming, after the manner of "tunnels" dug by earthworms, multiple ventilation, circulation and irrigation ducts which favor the crops and the distribution of the fertilizers.
In this respect, said elements may be advantageously charged with fertilizers when being dispersed in the ground, thereby becoming a progressive carrier for these products.
A first object of the invention is therefore to drain soil by means of a porous mass which also can be used for irrigation purposes. A kind of soft underground litter which is compressible is provided so that the water is distributed and redispersed by cappilarity. Furthermore, this mass of elements, when dispersed in the earth, contributes to a lightening of the density of the soil.
A second object of the invention is that the mass is formed of hollow elements which individually define capillary or semi-capillary passages. In other words, each individual element has a through open-ended passage which is of capillary or semi-capillary dimensions. In this respect, the adjectives "capillary" or "semi-capillary" define the dimensions of a passage which distinguish basically from the art. "Capillary" means "resembling a hair". The word "capillary" is derived from the Latin "capillus" which means "hair". In other words, a capillary or even a semi-capillary passage is one of very small diameter and refers in the present instance to a passageway the diameter of which is small enough to overcome surface tension to a substantial degree. The familiar example of a capillary tube is a tube whose diameter is so small that when placed in water, water will significantly rise in the tube due to capillary action which overcomes the surface tension of the main body of water. Webster's Unabridged Dictionary, among its definitions of "capillary", mentions one wherein the diameter of the capillary dimension is stated to be approximately 1/2 millimeter. In the present invention the diameter of the individual element is between 2 and 20 millimeters, which is translated into English measurement between 0.08" and 0.8". The passageways through the hollow elements are meaningfully described as capillary because it is the intent that these passageways be rather small because their smallness serves a specific function, namely, retention of water therein until it is desired to give up the water.
A third object of the invention is to provide two types of spaces involved in the mass of elements under consideration. One type of space is the capillary passages as above discussed. These are of tiny diameter. The other kind of space is the space between elements which is not necessarily of capillary dimension. It is larger. So, there is in the present mass of hollow elements a "mix" of these two kinds of differently dimensioned spaces, one tiny so as to exert capillary action, and the other larger so as not to exert an action of a capillary nature. One tends to hold water, these being the capillary passages, and the other tends to permit the flow of water therethrough. As a whole, the mass of elements does not encourage flow of water therethrough. Water only can flow with some degree of freedom through the spaces between the elements, but it cannot flow through the elements due to the capillary dimensions of the passages defined by the elements.
The various objects of the invention are achieved in that a mass of hollow elements of various sizes, shapes, wall thicknesses and rigidity, said hollow elements internally defining through open-ended capillary or semi-capillary passages, are dispersed in soil in mutual contact and so oriented relative to one another as to provide between adjacent hollow elements spaces of various shapes and dimensions which combine with the capillary or semi-capillary passages of the hollow elements to form a porous mass for drainage, irrigation or lightening of soil. These are the "spaces" to which reference has been made immediately above, which are to be contrasted with the "capillary" open-ended passage extending through each of the sundry hollow elements.
In fact, the invention does not constitute merely a large number of hollow elements each having a capillary or semi-capillary through open-ended passage and each having adjacent hollow elements. More is involved, namely, this plurality of hollow elements are "dispersed in the soil".
Actually, the invention resides in the combination of the soil and the large group of hollow elements, which latter are specifically defined and which jointly make up the invention. The hollow elements alone do not constitute the invention, nor does the soil (dirt) alone make up the invention. It is the combination of the two with the elements dispersed through the soil. Therefore, the invention resides in the formation of a mixture of soil and a large number of hollow elements, with the hollow elements being of different sizes, shapes, wall thicknesses and rigidity, with the hollow elements defining spaces between them, and with the hollow elements defining through open-ended passageways through the elements themselves as distinct from the spaces between the elements. All of this permits two different kinds of retention and flow of water through the soil-plurality of elements mix. One is a rather easy flow, this being through the spaces, and the other having a tendency to retain the water, this being the capillary and semi-capillary passages.
U.S. Pat. No. 3,233,414 to Hansen et al. has been cited in the corresponding application Ser. No. 169,711. Admittedly, Hansen et al. do not have any dimensions given for their tile elements, but it is not too difficult to arrive at an approximation of the sizes of the elements. The elements are shown as being in a trench. The trench has a width and a depth. It would seem to require no particular argument to convince anyone in this art that the trench is more than small; that is to say, it would be ridiculous to assume that the trench is a few inches deep and less than a few inches wide. Likewise, the trench cannot be unduly deep nor unduly wide. A reasonable guess, i.e. an intelligent guess, is that the trench is about 5 ft. deep and 4 ft. wide. This would be typical of a hand or machine-dug trench which has no particular cause to be unduly deep or unduly wide. Let it be assumed, then, that the width and depth of the trench are of the dimensions indicated. If one counts the number of elements across the width, the elements would be about 6" long and 6" in diameter; similarly for the depth. That means that the passages in the elements are about 6". This is consistent with the mode of operation described for the Hansen et al. drain field tile in which the elements are supposed to permit ready traversal of water therethrough as indicated by the arrows in FIG. 5. Notice that the path of the arrows extends right through the openings in the passages, indicating that the water flows through the passages of the elements. This is directly contrary to the various objects of the present invention as shown above, particularly since each of the hollow elements of applicants has a passageway of capillary or semi-capillary dimensions and it is the purpose of this passageway to combine with the spaces between abutting hollow elements to provide a mix of passageways to differently control the flow of water. Indeed, there is no flow of water through the capillary passages. Therein lies the basic distinction between the Hansen et al. drain field tile and applicants' combined soil and multiplicity of hollow elements.